The effects of climate change are already evident in the Spree catchment in the form of temperature rise and increased evapotranspiration rates, putting local groundwater resources under water stress. Additionally, the shallow groundwater resources are affected by the intrusion of saline water from deeper aquifer layers at multiple locations in the investigated catchment area (Figure 1). Brandenburg has 18 out of 59 groundwater bodies with poor chemical condition moreover water bodies are partially contaminated influenced by mining activities.
One method to mitigate the effects of water stress and saline water intrusion in the area is by using artificial groundwater recharge.
Figure 1. Location of Spree catchment in Brandenburg
Figure 2. Concept of the research project
The approach of this study is to extract saline water from deep aquifer layers, then carry out the desalination process to get the treated desalinated water, and afterward reinject the water into the shallow aquifer to recharge the local groundwater resource (Figure 2). The resulting brine should either be sent to a sewage treatment plant or injected into a deep layer which is confined by a thick clay layer with low permeability.
Multiple modelling techniques are used (1) to assess the possible volumes of water that can be extracted and recharged (Groundwater flow model), (2) to assess soil collapses or additional storage space (Density-driven model), and (3) to assess mineral precipitation/solution effects causing porosity and flow velocity change (Geochemical model).
The largest costs come from desalination. As a result, optimization is being investigated to minimize desalination costs by mixing the desalinated water with storm water. In addition, reverse osmosis with hybrid systems such as solar and thermal energy is recommended to decrease energy consumption.